Fountain pen for viscous ink



Feb. 10, 1953 k. B. JOHNSON 2,627,344

FOUNTAIN FEN' FOR VISCOUS INK Filed July 22, 19 8' 3 177 Juventor I REYNOLD B. JOHNSON TIE 'L attorney Patented Feb. 10, 1953 FOUNTAIN PEN FOR VISCOUS INK Reynold B. Johnson, Binghamton, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application July 22, 1948, Serial No. 40,027

4 Claims. (Cl. l2044=) This invention relates to fountain pens and more particularly to fountain pens which can be. used with ink which contains a higher proportion of solids than ordinary writing ink, for example, drafting ink or the ink used for making conductive marks on so-called mark sensing records for record controlled machines.

In order to maintain a flow of ink from a fountain pen it is necessary to admit air into the barrel of the pen as the ink is used. This is ordinarily done on the principle of the chicken fountain. There is an aperture where the ink is exposed to the outer atmosphere and is held back by atmospheric pressure and surface tension. A bubble of air enters the pen through this aperture when atmospheric pressure exceeds the inner pressure due to the head of ink within the pen above the aperture, the vapor pressure in the chamber above the ink in the pen barrel, and the surface tension of the ink at the interface between the ink and the atmosphere.

The contact of the ink with the outer air, which this principle of operation requires, results in evaporation of the liquid of the ink and consequent deposition of the pigment. The resulting incrustation may clog the pen so that it will not write without being cleaned. The condition is exaggerated when the ink is one containing a relatively high percentage of solids, for a given amount of. evaporation will cause a more rapid incrustation.

. Another difficulty encountered is the effect of must be made to contain such ink and, preferably, to return it to the body of ink which is to flow through the nib in writing.

The expulsion of ink caused by fluctuations of temperature and pressure combines with the evaporation problem to increase the rate of incrustation, unless measures are taken to insure that the overflow ink is not exposed to greater evaporating influences than the ink at the normal interface.

I t is accordingly an object of the invention to provide a pen which will not become clogged, even though used with ink which contains a much higher percentage of solids than ordinary writing ink.

A further object is to provide means to catch and hold ink which overflows, due to atmospheric pressure and temperature fluctuations, in such a way that the rate of evaporation and incrustation of such overflow ink will not be substantially increased.

Still another object is to provide a pen capable of writing with relatively viscous ink, which will make a mark on the first stroke of the pen after a period of long disuse.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is an elevational view of the preferred embodiment of the invention, the cap being shown in section.

Fig. 2 is an enlarged longitudinal sectional view of the nib end of the pen shown in Fig. 1.

Fig. 3 is a cross-section on the line 33 of Fig. 1.

Fig. 4 is a cross-section on the line 44 of Fig. 2.

Fig. .5 is a cross-section on the line 55 of Fig. 2. One form of air inlet means is shown in the preferred embodiment of the pen illustrated in Figs. 1-5. In this case the air inlet means includes a large air chamber I3I which traps anyoverflowing ink. The air and ink can move about freely in this large chamber as the pen changes position, in accordance with their specific gravities, but for reasons to be described the overflow ink will be returned to the ink space of the pen during writing, before any air can enter the ink space.

The pen illustrated in Figs. 1-5 comprises a barrel portion I 35 which screws onto a pen holder portion I31 by means of threads I39. Within the pen is a plug I4I which is clamped between the barrel I35 and the pen holder I31 by its flange tuting, in effect, an extension of the tube, except that its sides extend straight toward the air chamber I3I as shown in Fig. 5, to define an opening I59 through which the air space communicates with the ink space. At the extremity of the penholder is a small capillary tube I5I which serves as the mb of the pen. The bottom of the socket I49 drains into this tube through an aperture The ink space extends through a In accordance with a well-known principle the nib Il of the pen has a wire I55 extending through it with a loose fit and normally projecting a short distance beyond the end of the tube. The wire is loosely held in one of the four pockets of a weight member I5! having a shaft of crossshaped cross-section, as shown in Figs. 4 and 5. The shaft of the weight member is notched at I59 to allow the wire to curve into alignment with the axis of the tube I5I. The upper end of the cross-shaped shaft is fitted tightly into a socket I60 of a weighting portion I6I of the weight member. The bent-over end I62 of wire I55 is loosely confined in the socket I60 by the shaft I51. The weighting portion I6I is grooved to provide shoulders I63, I64 and I66. When the pen is held in a position which makes the weighting end IGI tilt toward the right in Fig. 2, as permitted by the loose fit of the shaft of the weight member in the tube I46, the weight member has only a limited movement determinedby the space between the shoulders I63 and I64 on the weight member and the ends of the screw head I 65. This prevents the weight member, and the wire attached thereto, from having an excessive movement during normal writing operations which might tend to pump ink out of the tube I5I and cause blotting. If a more vigorous action of the wire is required, in order to free the ink channel through the tube I5I of incrusted ink, the pen can be held in a position so that the weight member ISI will tilt toward the left in Fig. 2, which will move the shoulder I64 clear of the screw head I65 and allow the weight member and the wire attached thereto to have the relatively longer movement determined by the space between the shoulders I63 and I66 on the weight member and the ends of the screw head I65.

Air is admitted to the overflow and air inlet chamber I 3| through a tube I'II having a very small bore. This tube is disposed as shown in Fig. 2 in order to provide a section of the air inlet passageway having a length several times greater than its diameter. The disposition of the tube III as shown places its inner end at the volumetric mid-point of the air chamber I3I. Thereby, if ink should overflow into the air chamber until it nearly reaches the inner end of the tube In, with the pen in the position shown in Fig. 2, if the pen is turned to any other position the level of the ink will still be just below the inner end of the tube Ill. The portion of the air inlet'passageway in the tube III is thus protected against the entrance of ink from the inside of the pen, which would otherwise have the effect of sealing off the air inlet means, because of the very small size of the bore of the tube I'II. When ink is drawn out of the nib in writing the overflow ink in the air chamber all flows back through the opening I53 into the ink space before any air can enter the ink space. Moreover, the returning overflow ink reenters the ink space near the inner end of the nib I5I and passes out through the nib before ink from the reservoir I45. In this way the overflow ink, which has been exposed to more drying conditions than the ink in the reservoir, is the first ink to be used. The dimensions of the air chamber I3I can be such as to take care of the overflow which would be caused by any possible changes in pressure relations.

The weight member I51, I6I is free to turn on its long axis, but in any position there will be at least one vertical channel on the back side' of the shaft I51 for the ink for flow down to the nib without interference by air bubbles entering the opening I50. The shaft I51 reaches down below the opening I50 to prevent air bubbles from getting behind it, requiring them to rise in one or another of the vertical channels on the front side of the shaft. The flow of ink to the aperture I53 is further insured by grooves I10 in the conical bottom of the socket I49.

The pen has a cap I13, as shown in Fig. 1, which fits over the end of the pen and nearly closes the outer end of the air inlet duct III The cap has a rubber stopper I15 mounted by a pivot IT! in a socket I79 of a nut I8I which screws into the end of the cap. This construction permits the cap to be turned in relation to the pen in applying or removing it, without damage to the pen. The nut also serves to hold a clip I83 to the pen cap. The cap has a ventilating hole I85.

In the drawing the nib isshown with a slanted end, but the end may be square across, or may have even a greater slant than shown. The slanting end improves the contact of the ink with the paper and makes a somewhat broader mark than a square ended tube. It has advantages for marking record cards of the mark sensing type, because it gives greater assurance of producing a good mark at'the first stroke of the pen.

While there have been shown and-described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by thoseskilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

'1. In a fountain pen, a barrel, a writing element in the form-of a capillary tube in one end of said barrel, means dividing the inner space of said barrel into an ink reservoir in the upper part thereof and an air chamber in'the lower part thereof adjacent said writing element, means venting said air chamber'to the atmosphere, means forming an ink channel toconduct =in'k from said reservoir past said air chamber to said writing element, said-ink channel having' -an opening in the lower'end thereof communicating with said air chamber, a wire loosely held in said capillary tube and projecting from the-outer end thereof, a weight memberhaving grooved portions which form a plurality of longitudinally spaced shoulders on one side of said'weight member and including a shaft portion guided in said ink channel for a longitudinal movement therein, said shaft portion having a plurality of flanges subdividing said ink channel into separate longitudinal passageways, said wire lying in one of said passageways and'beingattached to said weight member soas to move therewith and means mounted on said dividing means for selectively engaging said shoulders to limit the stroke of said longitudinal movement to a short or a long stroke, said last named means being longitudinally spaced at different distances from said shoulders.

2. In a fountain pen, a barrel a writing tube extending through one end of said barrel, awi're extending through the'bore of said tube aweight member attached to said wire, means 'gu-idixig said weight member for movement longitudinally of the pen, said weight member having grooved portions which form a plurality of longitudinally spaced shoulders on one side of the weight member and means mounted in said barrel for selectively engaging said shoulders to limit the stroke of said longitudinal movement to a short or a long stroke, said last named means being longitudinally spaced at different distances from said shoulders.

3. In a fountain pen, a barrel, a writing tube extending through one end of said barrel, a wire extending through the bore of said tube, a weight member attached to said wire, tubular means to guide said weight member for movement longitudinally of the pen, said weight member being loosely mounted in said tubular means and having grooved portions which form a plurality of longitudinally spaced shoulders on one side of the weight member, the loose mounting of the weight member permitting it to rock transversely of the long axis of the pen in response to tilting of the pen in difierent directions, and means mounted in said barrel for selectively engaging said shoulders to limit the stroke of said longitudinal movement to a short or a long stroke, said last named means being longitudinally spaced at different distances from said shoulders, whereby tilting of the pen permits one shoulder to pass the means mounted in the barrel to allow the longer stroke to occur.

4. In a fountain pen, a barrel, a writing element at the end of said barrel, means subdividing said barrel transversely to form an air chamber at the end of said barrel which is lower when the pen is in writing position, and an ink reservoir at the upper end of said barrel, means venting said air chamber to the atmosphere and an ink channel having an opening into said air chamber at the lowest point of the latter when th pen is in writing position, said ink channel comprising a plurality of separate longitudinal passageways formed by a partition means, at least one of which is in a position to become efiective to conduct ink from said reservoir past said air chamber to said writing element, said partition means extending below the top of said opening and being effective to shield the ink conducting passageway from air bubbles entering said opening by directing said air bubbles into any of the remaining passageways, whereby the air bubbles are ineffective to stop the flow of ink through the ink conducting passageway.

REYNOLD B. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 225,401 Livermore Mar. 9, 1880 229,980 Downes July 13, 1880 233,616 Haring Oct. 26, 1880 421,069 Evans Feb. 11, 1890 1,352,340 App Sept. 7, 1920 1,379,603 Abegg May 31, 1921 2,176,568 Freeman Oct. 17, 1939 2,217,502 Wallace Oct. 8, 1940 2,303,373 Martin Dec. 1, 1942 2,396,771 Brinson Mar. 19, 1946 2,405,381 Van Spankeren Aug. 6, 1946 2,472,343 Rosa June '7, 1949 2,509,234 Kahn May 30, 1950 2,512,004 Wing June 20, 1950 FOREIGN PATENTS Number Country Date 474,893 Great Britain Nov. 9, 1937 

